Fluid state devices



c. J. AHERN FLUID STATE DEVICES Sept. 9, 1969 2 Sheets-Sheet 1 Filed Feb. 4, 1966 POSITION 38b POSITION 38 0 PULSE WIDTH INVENTOR. CHARLES J, AHERN ATTONE Sept. 9, 1969 c. J. AH ERN 3,465,773

FLUID STATE DEVICES Filed Feb. 4, 1966 2 Sheets-Sheet 2 INPUT PULSE SOURC VARIABLE VOLUME INVENTOR. CHARLES J. AHERN CONTROL "I p6 INPUT ["1 P9 OUTPUT I z I IF- t H i 2 I W 6 Fig. 5

ATTORNEY United States Patent 3,465,773 FLUID STATE DEVICES Charles J. Ahern, Detroit, Mich., assignor to The Bendix Corporation, a corporation of Delaware Filed Feb. 4, 1966, Ser. No. 525,094 Int. Cl. F15c 1/08, 1/12, 1/14 U.S. Cl. 137--81.5 14 Claims ABSTRACT OF THE DISCLOSURE This invention pertains to fluid state devices having no moving parts during fluid operation, and more particularly, to devices for controlling fluid signal pulse widths, delay between input and output pulses, and for fluid path selection in absence of a control signal.

It is an object of this invention to produce a fluid pulse having a variable duration which may be varied by a simple adjustment. In a preferred embodiment, a desired pulse width may be obtained by connecting a control port in a fluid state device to an otherwise closed chamber. The fluid stream going by the chamber connected port will create a vacuum in the chamber drawing the stream against the wall adjacent the chamber port, directing the stream to a vent leg constituting an off position. A signal is applied to force the fluid stream into the chamber through the chamber port. This causes the pressure in the chamber to increase thereby forcing the fluid stream away from the wall adjacent the chamber port and against an opposite wall directing the stream to an output leg of the fluid device upon removal of forcing signal. This may be considered the on position and the fluid stream will remain in the .on position and in the output leg until suflicient vacuum has been reestablished in the chamber to switch the stream to the vent leg and off position. The time that the fluid stream flows in the output leg is the width of a fluid pulse and this time may be varied by varying the volume of the chamber. By constructing a chamber with a piston in a cylinder, the chamber size, and hence the pulse width, may be varied by simply moving the piston in the cylinder.

It is another object of this invention to provide an output pulse a predetermined time after the occurrence of an input pulse in a fluid device. In a preferred embodiment, three fluid devices are interconnected so that an output of two of the devices are connected to the control port of a downstream device. The second and third devices have closed control chambers of the kind described in the previous object. The control chamber of the second device may be varied to vary the time between the input pulse and the beginning of the output pulse. The width of the output pulse may be varied by varying the control chamber of the third fluid device if desired.

It is a further object of this invention to provide a fluid device having means therein for directing an input fluid stream to a desired output leg in absence of a control pulse. In a preferred embodiment, this is accomplished by rounding a corner on that side of the fluid stream passage I 'ice duration and an automatic reset of the input pulse.

These and other objects and advantages of this invention will become more apparent when a description of preferred embodiments of this invention is made in connection with the drawings in which:

FIGURE 1 is a schematic drawing of a preferred embodiment of this invention showing a closed control chamber having a variable volume;

FIGURES 2 and 3 are graph representations of the pressures in the control and output legs for the device of FIGURE 1 for two ditferent volumes of the control chamber in FIGURE 1;

FIGURE 4 is a schematic of a second preferred embodiment of this invention having three fluid devices to provide for a predetermined interval between an input and output pulse;

FIGURE 5 is a graphic representation of the pressures in various ports of the device of FIGURE 4;

FIGURE 6 is an enlarged schematic diagram of the first fluid device in the schematic of FIGURE 4 showing the rounded corner which produces a preference for the fluid stream path in absence of a control signal;

FIGURE 7 is a schematic drawing of a preferred embodiment of this invention having two stages, the first stage a monostable fluid device and the second stage having a variable fluid chamber; and

FIGURE 8 is a graphic representation of the pressures in various ports of the embodiment of FIGURE 7.

EMBODIMENT OF FIGURE 1 In FIGURE 1 is shown fluid device 20 having supply port 22 with fluid pressure P therein. The fluid flows from port 22 through common passage 23 and leg 24 to outlet 26 having pressure P therein. Supply port 22 is also connected through common passage 23 and leg 28 to outlet 30 having pressure P therein. Control port 32 is connected to a pulse source, not shown, which provides port 32 with pressure P and port 32 connects to common passage 23. On the opposite side of common passage 23 is chamber port 34 having pressure P therein and connected to a variable volume chamber 36. A portion of the attachment wall on the chamber port 34 side of passage 23 has been removed to aid in the operation of this device. The volume of chamber 36 may be varied by moving piston 38 therein. The position of piston 38 is shown at 38a and at 38b to provide two different pulse widths as will be explained below.

OPERATION OF THE EMBODIMENT OF FIGURE 1 The operation of the device in FIGURE 1 will now be described with the aid of FIGURES 2 and 3. A supply jet or fluid flow from port 22 flows through common passage 23 and as it flows past port 34, the fluid in chamber 38 is aspirated to some negative pressure value causing deflection of the fluid stream into output or vent leg 28. The fluid flow is held against leg 28 by attachment of the fluid stream against the outer wall of passage 28 and remains there until an input pulse is applied to port 32 which partially deflects the supply flow from common passage 23 into volume 38 raising pressure P to some positive level. When the control input from port 32 is removed, the positive pressure in chamber 38 deflects the fluid flow to leg 24 increasing pressure P This deflection is aided by the removal of a portion of the attachment wall of passage 28.

The flow through leg 24 again aspirates the fluid from chamber 38 and when the fluid in chamber 38 is sufficiently evacuated, pressure P will be low enough to draw back the supply flow into leg 28 terminating flow to leg 24 and dropping pressure P The length of time that the EMBODIMENT OF FIGURE 4 A second embodiment of this invention is shown in FIGURES 4 and 5. This embodiment is used as a variable fluid delay line with an input pulse being delayed by a variable amount of time through a simplemechanical adjustment. In the schematic of FIGURE 4 are shown three fluid elements 42, 44 and 46. Element 42 has a supply pressure P provided to supply port 48 which is connected to common passage 50 which in turn is divided into vent leg 52, which may be vented to atmosphere and output leg 54 which has pressure P; formed therein. Control port 56 is connected to common passage 50 and has input pressure P therein while control port 58 is connected to reset pressure, as will beexplained below, and is also connected to common passage 50 opposite port 56.

Element 44 has supply pressure provided to supply port 60 which is connected to common passage 62 from which the fluid flows either to vent leg 64, which may be vented to atmosphere or output leg 66 wherein pressure P is established. On one side of common passage 62 is control port 68 wherein pressure P is present and on the opposite side of common passage 62 is control port 70 which is connected to variable chamber 72, the volume of which may be varied by turning threaded member 74.

In element 46, supply pressure is provided to port 76 which is connected to common passage 78 carrying fluid to vent leg 80, which may be vented to atmosphere, and output leg 82 which has pressure P Output port 84 carries the output pulse and reset port 86 is connected to a reset passage and port 58 of element 42. Control port 88, in which pressure P is present, is connected to common passage 78 and is opposite control port 90 which is connected to chamber 92 on the opposite side of passage 78.

Before explaining the operation of the embodiment of FIGURE 4, element 42, which is shown in an enlarged view in FIGURE 6, will be explained. The rounded intersection 51 between common passage 50 and control port 56 as shown has a radius which may be in the order of .2 of the width of common passage 50. The opposite corner 53 is not rounded and is square. Whenever there is fluid flowing in common passage 50 and there is no control pulse from port 56 or 58, due to the rounded corner 51, the fluid will always start to flow into passage 54 in preference to passage 52. By making intersection 51 more rounded than intersection 53, the desired eflect is possible. This novel feature is advantageous as will be evident from the description which follows.

OPERATION OF THE EMBODIMENT OF FIGURE 4 When the supply pressures at ports 48, 60 and 76 are turned on, the fluid flow in element 42 will attach to the wall of leg 54 due to the radius 51 as explained above, the fluid from port 60 will attach to the wall of leg 64 due to the aspiration of chamber 72, and the flow from port 76 will attach to the wall of outlet 80 due to the aspiration of chamber 92 as explained for the embodiment of FIGURE 1. Due to the deflection of port 60 flow by the pressure in port 68 into chamber 72, the pressure in chamber 72 at some time after the supply pressure is turned on will be increased to a positive value, so that when a signal is received at input control port 56 in element 42, which switches the flow from leg 54 to vent passage 52, the flow in element 44 will be switched from vent leg 64 to leg 66 due to the positive pressure in chamber 72. The flow in leg 66 causes a flow through control port 88 defleeting port 76 flow into chamber 92 causing it to reach a positive pressure so that when chamber 72 becomes aspirated, the time of which depends upon the volume of chamber 72 which may be varied by turning threaded member 74, it will attract the flow from leg 66 back to vent leg 64 diminishing the pressure in line 66 and port 88, whereby the positive pressure in chamber 92 will force the stream from leg into output leg 82 where an output pulse is present at port 84 a predetermined time after the input pulse has been applied to passage 56. The predetermined time of the pulse delay, as described above, is dependent upon the volume of chamber 72. The output pulse in passage 84 will remain until chamber 92 hecomes aspirated which in this embodiment will be a fixed time since chamber 92 is not shown as variable, at which time the vacuum pressure in chamber 92 will draw the stream from leg 82 back to leg 80 to vent terminating the output pressure. Chamber 92 may, of course, be made variable.

Also, while the pressure P in output passage 84 is: present, the same pressure P is also present in reset port 86 causing the flow from port 48 to be changed from vent passage 52 to passage 54 resetting the unit for the next input pulse.

EMBODIMENT OF FIGURE 7 In FIGURE 7 is shown an embodiment wherein an output pulse of predetermined width is provided in a two stage device with an automatic reset of the first stage. The leading edge of the input pulse initiates the output pulse.

A supply pressure P issues a continuous fluid flow from port through common chamber 102 which is connected to vent leg 104 and control leg 106. Input line 108 is connected to common passage 102 at a point between port 100 and leg 106. A vent passage 110, which is substantially larger than passage 108, is formed between port 100 and leg 104 and is sufliciently large so that there is no effective attachment wall and hence no fluid memory in leg 104 whereas there is memory in leg 106 due to the presence of an attachment wall 107 against which the fluid can lock. Pressure P is present in leg 108 and pressure P is present in leg 106.

In the second stage of fluid device of FIGURE 7, a supply pressure, not shown, supplies a substantially continuous fluid flow to port 112 with port 112 being connected to common passage 114, which is connected to vent leg 116 and output leg 118 having pressure P therein. Leg 106 is connected to one side of common passage 114 and variable volume chamber having threaded member 122 located therein to vary the volume, and hence the output pulse duration, is located on the other side of passage 114. A portion of the attachment wall along passage 116 is removed so that flow deflection from passage 116 to passage 118 is facilitated.

OPERATION OF THE EMBODIMENT OF FIGURE 7 The operation of the FIGURE 7 embodiment will be described with the aid of the graph of FIGURE 8. The flow from port 100 will be down leg 106 since the attachment wall in leg 104 has been substantially removed and hence a flow to leg 104 will be unstable while the flow to leg 106 will be stable. When pressure P is applied to passage 108, the flow port 100 will be deflected to leg 104. This reduces the pressure P in leg 106 so that the pressure which has been building in chamber 120 will cause the flow from port 112 in the second stage fluid device to change from leg 116 to leg 118 thereby increasing pressure P The pressure P will remain increased until the aspiration of chamber 120 reduces the pressure therein sufficiently to draw the flow from passage 112 back to passage 116. The aspiration time of chamber 120 will depend upon its volume, which volume is variable by turning member 122.

Upon the release of the input pressure P the flow in leg 104 will automatically return to leg 106 without the aid of reset pressure thereby simplifying the system design.

Although this invention has been disclosed and illustrated with reference to particular applications, the principles involved are susceptible of numerous other applications which will be apparent to persons skilled in the art. The invention is, therefore, to be limited only as indicated by the scope of the appended claims.

Having thus described my invention, I claim:

1. A bistable apparatus comprising:

fluid supply means for providin a fluid flow;

common passage means from said supply means;

two legs connected to said common passage means;

control means to control fluid fiow from said supply means to one or the other of said two legs; and

means to cause initial fluid flow from the supply means to flow to a selected one of said two legs so that absent an overriding control force from said control means, initial flow from the supply means will be to said one leg in preference to said other leg without influencing sustained fluid flow.

2. The apparatus of claim 1 with said control means comprising two control passages,

each of said control passages intersecting said common passage means on either side of said common passage means forming passage wall intersections,

said means being formed by the passage wall intersection on one upstream side of said common passage means having a larger radius than the passage wall intersection on the opposite side of said common passage means with the fluid stream being attracted to move towards the side of the common passage means having the larger radius of wall intersection.

3. The apparatus of claim 2 with said larger radius being on the order of /5 the transverse dimension of the common passage means in the plane of the intersection between said common passage means and the control passage.

4. Apparatus comprising:

a supply port;

two outlet ports;

common passage means interconnecting said supply port and said outlet ports;

a control orifice and a chamber orifice located in said common passage means, on opposite sides thereof, and intermediate said supply port and said outlet ports;

a pressure source connected to said control orifice and operative to produce pressure fluid signals;

a chamber having a predetermined volume connected to said chamber orifice;

said chamber operative upon aspiration to cause a pressure differential to affect a fluid stream flowing from said supply port to said outlet ports so that said stream flows to a selected one of said outlet ports; and

said fluid signals operative to divert a portion of said fluid stream into said chamber to raise the pressure thereof, whereby termination of said fluid signal allows a second pressure differential to exist and cause said fluid stream to flow to the other of said outlet ports for a predetermined period of time.

5. The apparatus of claim 4 with means for varying the volume of said chamber.

6. A fluid apparatus comprising:

a first element means having means for establishing a first fluid flow, first and second paths;

first element control means for receiving an input pulse;

said control means operative on receipt of said input pulse to switch said first fluid flow from said first path to said second path;

second element means having means for establishing a second fluid flow, third and fourth paths, and re sponsive control means;

said responsive control means responsive to the switching of said first flow to switch said second fluid flow from said third path to said fourth path and back to said third path after a predetermined period of time, said second means having a variable volume chamber adjacent said third path which is pressurized by the flow from said one path for switching said second flow when said first flow is switched, said second flow aspirating said chamber, the aspiration time of said chamber being dependent upon the volume of said chamber, the aspiration time of said chamber determining the time for switching back said second flow and aspiration of said chamber causing the switching back of said second flow; and

third element means having means for establishing a third fluid flow, fifth and sixth paths, and second responsive control means;

said second responsive control means responsive to the switching of said second fluid flow from said fourth path back to said third path to switch said third fluid flow from said fifth path to said sixth path and back to said fifth path after a second predetermined period of time to produce an output pulse having a pulse Width equal to said second predetermined period of time and occurring a period of time, equal to said first predetermined period of time, after the receipt of said input pulse.

7. The apparatus of claim 6 with said first means comprising preference means for causing the first flow to prefer said first path over the second path.

8. The apparatus of claim 6 with said third means comprising a second chamber adjacent said fifth path which is pressurized by the switched second flow, said pressurized chamber switching a third flow after said second flow is switched back, said switched third flow aspirating said second chamber and the aspiration time of said second chamber determining the length of time said third flow is switched.

9. The apparatus of claim 6 with a portion of said switched third flow being connected to said first means to return said first flow to said one path thereby resetting said device.

10. The apparatus of claim 6 with means for providing an input pulse being connected to said first means for receiving an input pulse.

11. Fluid apparatus comprising:

first means for receiving an input pulse;

switching means in association with said first means operative to cause a first fluid flow to switch from a first path to a second path;

second means responsive to the switching of the first flow away from said first unblocked path operative to switch a second flow from a third unblocked path to a fourth unblocked path and back to said third unblocked path after a predetermined period of time; and

memory means in cooperative association with said first path so that said first flow will be in said second path only while said first means are receiving an input signal.

12. The apparatus of claim 11 with said second means having a variable volume chamber which is pressurized by the flow from said first path for switching said second flow when said first flow is switched,

said second flow aspirating said chamber, the aspiration time of said chamber being dependent upon the volume of said chamber,

the aspiration time of said chamber determining the time for switching back said second flow and the aspiration of said chamber causing the switching back of said second flow.

13. The apparatus of claim 11 with first means comprises a fluid supply, a common passage being connected to said supply, said first path and said" second path being connected to said common passage, a control orifice being in said common passage to connect Said common passage with said input pulse, and a vent orifice being connected to said common passage,

said vent orifice being in the attachment wall area of said second path thereby minimizing path memory.

14. Apparatus comprising:

fluid supply means;

common passage means connected to said supply means;

two outlet legs extending from said common passage means;

a first port connected to said common passage means adjacent to one of said outlet legs;

a second port connected to said common passage means adjacent to the other of said outlet legs;

means interconnecting said first port to a source of fluid pressure; and

means associated with said second port operative to cause a fluid stream from said fluid supply means to flow'out'said'other outlet leg until a fluid pressure has been applied to and removed from said first port at which time the fluid stream will flow out said one outlet leg for a predetermined period of time after which it will return to said other outlet leg where it will remain until a fluid pressure pulse has been again applied to and removed' from said first port.

References Cited H UNITED STATES PATENTS 3,193,197 7/1965 Bauer 13781.5 XR 3,204,652 9/1965 Bauer 13781.5 3,217,727 11/1965 Spyropoulos 13781.5 3,223,101 12/1965 Bowles 13781.5 3,228,410 1/1966 Warren et a1 13781.5 3,277,913 10/1966 Fox et al 13781.5 8,285,264 11/1966 Boothe 13781.5 8,320,966 r 5/1967 Swartz 13781.5 3,331,379 7/1967 .Bowles 1378l 5 SAMUEL SCOTT Primary Examiner 

